On a lightly oiled skillet, cook mushrooms on medium heat with a bit of salt and pepper, for 1 minute. Add the canned soup, white wine and oregano and cook for 7-8 minutes on medium-high heat -stirring constantly- or until sauce is thick (It will get thicker with cheese, so don't let it get too thick). Add cheese and cook for 30 more seconds, or until cheese is melted